Mors Certissima
by Cumberbatch Critter
Summary: John Watson didn't get invalided home from Afghanistan. He died there. (Sort of.) [Reaper!lock AU]
1. Chapter 1

**mors certissima**

 _Watson, H John_  
 _COD: Exsanguination_

Simple.

Destructive, deadly.

Boring.

He watched the carnage of bloodshed expressionlessly, seeing but unseen. The rift between worlds kept him hidden. The atmosphere was cool despite the humid, arid landscape of Afghanistan's terrain.

He breathed in, breathed out. The metallic rippling through the air meant that a new soul had entered the rift. This was his bounty. He stepped away from his post and strode forward purposefully. The landscape changed into nothing; a blank, wide open space reminiscent of Afghanistan itself, but devoid of the life and lives taken on the desert battlefield.

The man was short, with dusty blonde hair and indecipherable eyes. He thought that he ought to call them blue in this vast wasteland of bright nothingness. Blue, for detail's sake. Details were important, when he had so little to occupy himself in the first place.

The man was clearly a soldier: tan lines, but not above the wrists. He held himself like a soldier: shoulders back, spine straight, chin raised. The uniform did bring it together, though.

The identification tags around the man's neck glittered in the light.

He stepped forward, pulling his hood more firmly around his face. "You have entered the rift between worlds. Your time amongst the living realm has come to a close." His statement was flat. He felt nothing. He was here for John Watson, and John Watson was here because he was dead.

Simple as that.

John spun around, reaching for the weapon that he no longer had on his person. His eyes fell on his companion, and he hesitated. His hands fell back to his sides slowly, his gaze now analysing. He was very keen, that much could be deciphered. He was very dedicated.

Dediction meant nothing to the one waiting between worlds.

He reached forward, fingering John's glittering dog tags. "John Hamish Watson. Your time has arrived. Come." He removed his fingers from the cool metal, and held out his hand instead.

John stared at his hand, and then looked up at him. There was no way that he could see his face, he was shrouded in shadows beneath the heavy flowing fabric of his cloak, but there was something intense in John's eyes.

"My time has come," John repeated.

"Yes," he said flatly.

John squared his shoulders. "You're saying I died."

"Yes," he repeated.

"So this is..."

"The rift between worlds," he said.

"Between Life and Death."

"Yes."

"No."

He felt his eyebrows raise before he could process the reaction. "No?" he repeated. "You cannot argue with a harbringer of death. It's too late, John. It's time to go."

"No," John repeated, just as stubbornly.

He paused. Usually arguments regarding passing onto the next realm were filled with tears or frantic pleading. Bargaining was common. So was denial. Arguments weren't uncommon, but not with solid self-assurance.

"Yes," he said slowly, folding his fingers into his palm and letting his hand drop. "You were the recipient of ballistic trauma resulting in exsanguination." Sparing death details was not suggested, but helpful in some circumstances. "It's time to move on."

"To where?"

This was usual. The questions were never-ending, even if John had broken ideals regarding accepting death.

"Am I going to Heaven?" John continued determinedly.

"That's not for me to decide."

"Why are you here, then?"

"To assist you from your realm to the realm beyond."

"To take me to Heaven? Hell? Where exactly does this go?"

This was the bravery of the soldier. Some would call it stupidity. It almost elicited human emotion from him, the way John's determination was coming across in this conversation. Nonetheless, he did think it was admirable, and yet entirely useless to him.

"I take you to where you are to be judged," he said bluntly.

"So there is a Heaven or Hell," John replied.

The cloaked one remained stoically silent. The afterlife and where souls went once they had departed was not his place to discuss.

"Okay, you won't answer my questions, you're frankly an awful... thing to have to meet once you apparently die, and I don't care if you do say that I bled out, until I either see Heaven or Hell, I'm not buying it." John nodded to himself and turned on his heel, striding away from him.

He blew out a deep breath slowly. He closed his eyes momentarily, and spoke again. "Walk as far as you'd like, John Watson. Death delivers us all to the same end."

The words seemed to irk John. He spun around again, eyes blazing. "And _you're_ Death?"

"I am Death's servant."

"Well, until Death comes to retrieve me personally, you can tell him I said "piss off"," John retorted, and turned back around to march away.

Expressionless aside, he laughed out loud. The sound was foreign, rarely used. Humour was a concept only distantly familiar. But John Watson was making him laugh. Curious.

He didn't move away from the spot he was in. Despite the world of Afghanistan that he had been viewing only moments ago, there was no escape from the void. Once John realised that, perhaps then he would go with him more willingly. He did not need to follow him, because John would not be leaving.

Theoretically, the rift was unbroken and unending. One could walk until the end of time and there would be nothing. He didn't need to move to keep his eye on John; he would never outwalk him, and he couldn't outrun him. Like a bird in a cage.

Something tingled at the back of his head, on the inside of his brain. He cocked his head, eyebrows furrowing. The dark fabric of his hood brushed against his eyelashes. John was still wandering in the distance.

And then he wasn't.

The cloaked one's head snapped up, eyes darting around the void. There was nothing except bright light and cool air, the usual ticking of a clock and his own breathing. He turned in a circle, something akin to adrenalin in his veins, and let his eyes sweep across the blank nothingness.

"John..." he growled, waving his hand for the scenary to melt back into that of Afghanistan. His being was now in tune with John Watson's soul; he found him without resistance. The medical tent, under the hands of army doctors similar to the one he had just been talking to, and-

 _"He's breathing, get that over here_ now _!"_

He stared at the scene before him, jaw clenched. He hadn't had a soul escape from him before. It didn't happen often in his realm, and it had never happened to him. John Watson was the exception.

He was almost as irritated as much as he was intrigued by it.

He swept the scene away, jerking the hood away from his face. The luminosity of the rift between worlds cast shadows onto his face, accentuating prominent cheekbones and ice chip eyes. Dark curls fell down around his ears, framing his pale face, set upon with the most grim of scowls.

John Watson had escaped Death.

Now it was Death's turn to pursue John Watson.

* * *

 **A/N: _vita incerta, mors certissima_ \- means 'The most certain thing in life is death', or 'Death is the one true certainty'.**

 **So, in doing a replay of a favourite game of mine, I was reminded of this plot. One of the game characters is a grim reaper as such and I can never stop thinking about how Sherlock could pull off a reaper spectacularly, dark, hooded cloak, chains and all. (Though no chains in this verse.) I finally got around to writing it. I might add a small follow-up chapter, because I have an idea where I wanted this to go but didn't want to just put in the A/N, so look for that possibility.**

 **As always, I do not own _Sherlock_. Thank you for reading!**


	2. Chapter 2

When John finally did die, it was not from ballistic trauma or exsanguination. It was only after a fulfilling life, speckled with trouble here and there, and a wife, and a child, and no longer any near misses from bullets in Afghanistan. It was through old age, and once again, Death was waiting.

Heedless to John, Death had been there all along.

After their last encounter, the shadowy spectre in the rift had quickly taken on a story to the persona he had been given, and descended to earth to follow John Watson through the rest of his newfound life. He had created a name to go with his face, he had created a past, a present, and planned out the future.

Reapers did not usually traverse earth, but then, humans did not usually escape Reapers.

So, he had followed John, he had chosen a life with a fast-paced, impossible to ignore lifestyle. He had ensnared John's attention, and they had been together ever since.

And even now

"... Sherlock?" John looked at him groggily, looking around the rift. "... what...?" He looked very much the same picture that he had so many years ago when he had died, however briefly, on the battlefield. Age meant nothing after death.

He smiled softly at John. Funny how attached he had become to this human. "I'm not Sherlock."

John frowned, and then straightened up slightly, taking a step back. "Is this a dream?"

"You died."

The intense look on John's face did not lessen. "Well, I thought... I remembered..." He shook his head. "But that makes no sense. If I died, how are we here?"

He smiled slightly. "Because I was never alive to begin with." It was a simple explanation, and yet, impossible at the same time.

The flicker of irritation that he was now used to flashed across John's face. "Explain, Sherlock."

"I'm not actually Sherlock," he repeated.

"Who are you, then?" John retorted. Fighting again. "Because you sure as hell _look_ like Sherlock."

"Sherlock was a name that I took on to take a place on earth. I used the persona to attract your attention once you returned from Afghanistan," he explained patiently. "I arranged for us to meet, and for you to move in with me. I was able to keep an eye on you that way."

John was looking at him like he was crazy. It was debatable, for sure. Having followed a human back to earth was not common, and the Higher Powers had not been amused. He hadn't minded. John Watson was his charge, and he would see it through. So what if he had a little... _fun_ in the meantime?

"You and I met, many years ago, before you met me as the being you know as Sherlock. We met in this exact place, actually." He waved a hand around the barren landscape. "After you had been fatally shot in Afghanistan."

Still with the look on John's face. Although now with a slight comprehension. John was quick. He grasped onto things quickly, although not as much as the Sherlock persona had.

"You would probably recognise me better this way." He waved his hand and the familiar long coat and scarf vanished, replaced with the dark cloak customary to that of his kind. Leather gloves dematerialised and he held out a hand to John, fingers extended, palm displayed. Pale skin illuminated in the glow of the in between, and he watched the complete recognition light up John's face.

Surprise, fear, and ultimately, _betrayal_.

"I told you once, that I was a servant of Death. That still stands. My coming to earth with you didn't change that fact. When you escaped from me the first time, I decided it was only right to find you and stay by you. Your soul is my business, John Watson. I was never going to let you get away."

John took another step back. "No." He shook his head. "No, Sherlock, you cannot tell me that you're- you're _Death_!"

He tilted his head. "I'm not. Just a-"

"Servant of Death, yes, apparently, you keep saying!" John said. "That can't be true! You were human, you're human, we... you..."

"I was human, because I wanted to appear to be. I had a past, because I needed one. It was all a fabrication of my own doing."

"... No. No." John continued to shake his head. "You _cannot_ tell me that this was all a lie!"

"It was," he relented. "For all intensive purposes. But the past, how long has it been in your time... fifty-one? years... it _has_ been a lie, but it has been true, also." He tilted his head. "I've never lived as a human. Rarely do I experience things in the way that humans do. So, it was a false truth created in order to reach a purpose, but... it _was_ truth. The cases, our adventures. The... friendship."

Friendship was not a familiar concept to a servant of Death.

How flummoxed he had been when he had started to realise he was genuinely happy in John Watson's company. The outcome was unfortunate, knowing the exact moment that John died, he would be in charge of taking him to the next realm, but at least there would be some familiarity in it. Right?

"Trust me one last time. John."

"But you... you..."

He grinned. "Okay, so I'm not human. Didn't you tell me that repeatedly throughout your life?"

"That is not funny," John retorted.

"But you were right," he replied, "and maybe, unconsciously, you knew that. Maybe, for the same reason, that was why you stuck around." He straightened up, clapping his hands together and pressing fingertips together. "But enough of that. I need to escort you to the realm of the beyond."

John was looking at him warily, as though he couldn't believe it. Apparently, he could not. And that wasn't surprising, because it was a shock. But he _knew_ John now, and he knew that John _knew_ that he wasn't messing around with him. He may not _like_ it... but John would follow him.

Which he did.

"You're such a liar," John said eventually.

"Yes," he agreed.

"The person I thought I knew."

"You did, though." He glanced sideways at John. "Everything you know about me is true. Not the past, not the things I needed to round out the story. But the cases... what I said at your wedding... all of that. That was true. Our kind," he said, lifting his chin, "have no room or reason for emotion when it involves other people, especially human. Yet you made me feel that, right from the moment I met you the first time," he mused. "It was interesting. Being amused. Depressed. Having _fun_." He huffed a breath. "I never experienced those things. I've never been _human_. Then you came along, and I experienced all of that." He looked at him again. "I should be thanking you, John Watson."

"So it was all just a thrill for you," John replied. "Thanks. Thanks a lot."

"It was for you, too," he retorted. "Knowing what you know now - if you even believe me - would you change any of it?"

John didn't answer, because both of them knew the answer.

He was quiet for awhile before he spoke to John again. "Besides, it wasn't just a thrill."

It had been _fun_. Having an existence in the middle of not existing. Being a detective, making acquaintances, working on experiments and solving cases. Being _John's friend_.

It had been a thrill... true. But it was more than that, too.

He couldn't explain it. But he wouldn't change it, either. He was glad that John had gotten away from him the first time... so glad.

Even if it _had_ grated on his pride a little bit.

It was funny, now, how _angry_ he had been in that moment, when John had woken up on the battlefield. He wouldn't change any of that, for any version of any world.

"This is it," he announced, gesturing. A doorway had appeared, and he looked back at John. "Where we finally part ways."

"Wait, you're not coming?"

He shook his head. "I do not live nor die."

"Oh. Well." John's fingers curled into fists momentarily, then relaxed as he gazed at the doorway. "... I swear if this is all just some dream, or elaborate joke..."

"My sense of humour is morbid, but this would be a _tiny_ bit out of its range," he interrupted. "Unfortunately, it's not a trick." He held out his hand, again, this time, for a handshake. "I will miss you. Which may surprise me more than it surprises you," he added thoughtfully, and then shrugged.

"We end as we began," John muttered. "Right? Since we met here." He reached out and took his hand. "Are you gonna be around? Servant of Death and all?"

"Oh yeah." He grinned slyly. "Besides, I'd get _bored_ if I didn't have my blogger for company now and again."

John rolled his eyes. "Yeah, no hijinks in Heaven. Or whatever afterlife is in store."

"Oh, you'd be surprised."

Like so many other times, they shared a look and a chuckle. And then John turned around, shoulders back, head high. The bravery of the soldier. "... Thanks. Sherlock." Without waiting for a reply, he strode through the open doorway.

The humour fell away from the brunette's eyes as the doorway faded to nothingness. The grin was replaced with only a wistful smile, remembering every detail of the past fifty years with clarity as though it had happened yesterday. "... No. Thank you," he murmured, running his finger along the small, metal chain around his neck. He unearthed it from the folds of fabric and looked at it, eyes tracing the familiar engraving.

John's dog tags, given to him only moments (how long had it been?) ago in the hospital as John had lay dying. Taken from the world of the living to his life in between, a memento of, without a doubt, the most exciting part in his non-life to date.

He clutched at the metal in his hand and smiled and, after reaching back to pull his hood back into his face, took off for the shadows again.

* * *

 **A/N: I have a tiny bit of an issue with adding this on because it feels a little cold and impersonal... but keeping in mind Sherlock is a Reaper in this verse, I think it's just enough to be acceptable in this verse. I hope. xDD**

 **Still in love with Reaper!lock... but back to TAB stuff soon xP Thanks for reading!**


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